1 research outputs found
Timing and source of the maximum of the transthoracic impedance cardiogram (dZ/dt) in relation to the H-I-J complex of the longitudinal ballistocardiogram under gravity and microgravity conditions
The transthoracic impedance cardiogram (ICG)
and the acceleration ballistocardiogram (BCG) measured close
to the center of mass of the human body are generated by
changes of blood distribution. The transthoracic ICG is an
integrated signal covering the whole thorax and spatial
resolution is poor. Comparison between both signals can be
used to elucidate the source of the ICG signal. We recorded the
ECG, ICG, and BCG simultaneously in healthy subjects under
resting and microgravity conditions during parabolic flights.
The time interval between the R-peak of the ECG and the
maximum of the ICG (R-dZ/dtmax) and the time interval
between the R-peak of the ECG and the I-peak in the BCG (RI)
differed significantly (p<0.0001). The I-peak in the BCG
always occurred earlier during systole than dZ/dtmax. The
delay of dZ/dtmax ranged between 23 and 28 ms at rest and
was lowest under microgravity conditions (12±4 ms, p<0.02).
Our results suggest that both signals have different sources.
Combination of modern imaging techniques with classical non
invasive approaches to detect changes of blood distribution
may provide new insights into the complex interaction between
blood flow and mechanocardiographic signals like the BCG